1. Field of the Invention
The present invention relates to wireless controllers.
2. Description of the Prior Art and Related Information
Wireless keyboards have a number of advantages over the more common wire connected keyboards employed in computer systems. First of all, wireless keyboards offer more flexibility to the user to position him or her self relative to the computer. This can reduce strain and tiredness associated with computer use. Also, wireless keyboards reduce the amount of wires connected over or creates a cleaner look to the overall system and can give the computer system a more sophisticated and/or expensive look. This avoidance of wiring becomes increasingly significant as more add on peripherals are included in typical computer systems which can result in workplace clutter.
The wireless keyboards currently available are either infrared based or RF based transmission systems. The infrared systems are the simplest and least expensive, however, they require a line of sight to the receiver. This can result in inconsistent transmission as the keyboard is moved or if other objects block the transmission path. RF systems do not suffer from this problem but are more expensive than infrared systems. In particular, the reliability of transmission in RF systems at a given range depends on the RF frequency and the power and quality of the transmitter. Therefore, maintaining transmission reliability requires more expensive higher frequency transmitters and/or higher power transmitters. Nonetheless, RF systems are increasingly being used for wireless keyboards over infrared systems due to their performance advantages.
Undoubtedly the primary reason that wireless keyboards have not displaced wire connected keyboards to a greater extent is the need for replacing batteries. When batteries fail in a wireless keyboard computer system the system is useless until the batteries are replaced. This is obviously a significant inconvenience when the battery failure is not expected. Also, keyboards typically continuously scan the matrix of keys to detect key depression. Therefore, even when there is no data entry from the keyboard battery power is being used for key scanning. Therefore, battery lifetime is inherently limited in wireless keyboards.
As a result of these limitations wireless keyboards have not been able to fulfill the potential of replacing wired keyboards in computer systems.